Componentes de média para escolha de populações de milho para extração de linhagens

Abstract

The development of good agronomic performance maize hybrids requires large resources and time investments; therefore, the choice of germplasm is crucial for the success of a maize breeding program. Within several strategies of germplasm selection, the contribution of homozygous (m+a) and heterozygous (d) loci may provide good information about parental choices, since most of maize hybrids lack this information. Therefore, the objectives of this study were to obtain m+a and d estimates, the inbreeding depression for grain yield and plant height traits as well as to predict the potential of line extraction of maize hybrids. For this purpose, F1 and F2 generation of 12 maize hybrids were evaluated in two locations (UFLA and Muquém) during two crop years (2017/18 and 2018/19), counting four different environments. Both generations, F1 and F2, were evaluated in contiguous experiments under a randomized complete block design with three and two replications during 2017/18 and 2018/19 crop years, respectively. Plant height and grain yield data by plot were collected from these two generations, then m+a and d estimates, at plot level, were obtained for both traits. The dominance effects were more significant for grain yield, however considering only m+a, the hybrids AG1051, AG8025, BG7046, DKB455 and OMEGA were the most promising hybrids for line extraction since their estimates were higher than other evaluated hybrids. In this scenario, hybrids AG8025 and BG7046 must be highlighted since they associate high m+a estimates and high grain yield means. On the other hand, plant height trait had more influence of additive effects. Therefore, the observed inbreeding depression was higher in grain yield than plant height trait.